Time Pad Research Articles

How to re-use a one-time pad safely and almost optimally even if P = NP

Assuming an insecure quantum channel, a quantum computer, and an authenticated classical channel, we propose an unconditionally secure scheme for encrypting classical messages under a shared key, where attempts to eavesdrop the ciphertext can be detected. If no eavesdropping is detected, we can securely re-use the entire key for encrypting new messages. If eavesdropping is detected, we must discard a number of key bits corresponding to the length of the message, but can re-use almost all of the rest. We show this is essentially optimal. Thus, provided the adversary does not interfere (too much) with the quantum channel, we can securely send an arbitrary number of message bits, independently of the length of the initial key. Moreover, the key-recycling mechanism only requires one-bit feedback. While ordinary quantum key distribution with a classical one time pad could be used instead to obtain a similar functionality, this would need more rounds of interaction and more communication.

A Symmetric Encryption Algorithm based on DNA Computing

Deoxyribo Nucleic Acid (DNA) computing is a new method of simulating the bimolecular structure of DNA and computing by means of molecular biology. DNA cryptography is a new field which has been explored worldwide. The concept of using DNA computing in the fields of cryptography and steganography has been identified as a possible technology, which may bring forward a new hope for unbreakable algorithms. This paper proposed a new DNA cryptographic algorithm which used the key features of DNA and amino acid coding to overcome limitations of the classical One Time Pad (OTP) cipher. A significant feature of the proposed algorithm is that; it is considered an encryption and hiding algorithm at the same time. The proposed algorithm also enhances the security level of OTP cipher. An evaluation for the proposed algorithm is performed according to randomness testing by using the National Institute of Standards and Technology (NIST) test. The study showed that the proposed algorithm had better performance with respect to time, capacity and robustness compared to previous studies.

Authentication Service in Hadoop using One Time Pad

“Big Data” - voluminous and variety of data from different sources, which demands innovative processing and analysis for decision - making analysis. The data can be either in form of structured or unstructured data. Processing big data with the traditional processing tools and the present relational database management systems tends to be a difficult task. Parallel execution environment, like Hadoop is needed for processing voluminous data. For processing the data in a open framework like Hadoop we need a highly secure authentication system for restricting the access to the confidential business data that are processed. In this paper, a novel and a simple authentication model using one time pad algorithm that removes the communication of passwords between the servers is proposed. This model tends to enhance the security in Hadoop environment.

Secure and Robust Transmission and Verification of Unknown Quantum States in Minkowski Space

An important class of cryptographic applications of relativistic quantum information work as follows. B generates a random qudit and supplies it to A at point P. A is supposed to transmit it at near light speed c to to one of a number of possible pairwise spacelike separated points Q1, …, Qn. A's transmission is supposed to be secure, in the sense that B cannot tell in advance which Qj will be chosen. This poses significant practical challenges, since secure reliable long-range transmission of quantum data at speeds near to c is presently not easy. Here we propose different techniques to overcome these diffculties. We introduce protocols that allow secure long-range implementations even when both parties control only widely separated laboratories of small size. In particular we introduce a protocol in which A needs send the qudit only over a short distance, and securely transmits classical information (for instance using a one time pad) over the remaining distance. We further show that by using parallel implementations of the protocols security can be maintained in the presence of moderate amounts of losses and errors.

Non-Cooperative Eavesdropping Resisted Using Ford-Fulkerson And AES By Secure coding

A wireless sensor network is usually composed of a large number of spatially distributed autonomous sensor nodes. Advancement in the field of modern communication networks especially in the wireless network dramatically improved their accessibility,affordability and accuracy. The eavesdropping is a serious security threat to a WSN since this attack is a prerequisite to other attacks. Avoiding the major threat called eavesdropping,cryptographic techniquies are to be used. Reexamine the notion of security,accessibilty,affordability and confidentiality of the WSN, combines Shannon's cypher method and Ford- Fulkerson algorithm together with one time pad system. The idea behind the algorithm is simple. According to Ford-Fulkerson algorithm,as long as there is a path from start node to end node with available capacity on all edges in the path, send flow along one of these paths,find another path and so on.That path is called augmented path. Through this non-cooperative eavesdropping can be avoided. Ford-Fulkerson algorithm can be used along with the one time pad scheme. The one time pad scheme is a binary additive stream cipher, where stream of truly random keys are generated and then combined with the plaintext for encryption or with the ciphertext for decryption using exclusive OR addition. Because of the three important properties of this scheme one time pad scheme can accepted as the most prominent security providing mechanism,properties such as: key must be as long as the plain text, key must be truly random and key must only be used once. Main disadvantage is that one time pad scheme has a serious threat to Brute force attack. Thus for avoiding the brute force attack combines Ford-Fulkerson and ZKP along with the AES algorithm.

Mode characteristics of nano-width rectangle resonator

A new method based on Maxwell's equations, ABCD ray matrices, and total internal reflection is proposed to theoretically analyze the characteristics of eigenmodes confined in nano-width rectangle resonators. Using this method, mode wavelengths and indices of transverse and longitudinal modes are obtained. Another method based on the finite difference time domain technique and Pad'e approximation is used to numerically calculate resonant wavelengths, mode field distributions and quality factors. The results of two methods show that the resonant wavelengths obtained from both methods are very close, and the maximum relative error is less than 2%. The mode indices of transverse and longitudinal modes obtained agree well with mode field distribution patterns calculated by finite difference time domain techniques.

Secrecy Outage Capacity of Fading Channels

This paper considers point-to-point secure communication over flat fading channels under an outage constraint. More specifically, we extend the definition of outage capacity to account for the secrecy constraint and obtain sharp characterizations of the corresponding fundamental limits under two different assumptions on the transmitter channel state information (CSI). First, we find the outage secrecy capacity assuming that the transmitter has perfect knowledge of the legitimate and eavesdropper channel gains. In this scenario, the capacity achieving scheme relies on opportunistically exchanging private keys between the legitimate nodes. These keys are stored in a key buffer and later used to secure delay sensitive data using the Vernam's one time pad technique. We then extend our results to the more practical scenario where the transmitter is assumed to know only the legitimate channel gain. Here, our achievability arguments rely on privacy amplification techniques to generate secret key bits. In the two cases, we also characterize the optimal power control policies which, interestingly, turn out to be a judicious combination of channel inversion and the optimal ergodic strategy. Finally, we analyze the effect of key buffer overflow on the overall outage probability.

Using El Gamal Cryptosystem in Message Feedback Mode for Computing Cost Reduction

This paper discuses comparatively more efficient and cost effective scheme of El Gamal Cryptosystem by introducing the concept of using the established cryptosystems into message feedback mode. The idea behind this is, “an established cryptographic scheme can be used to initiate any communication, and further users may switch to some lightweight process so that the degree of secrecy is maintained by means of the public key cryptosystem and the performance is achieved by using some other lightweight process. Approach discussed in this paper is of using message itself as One Time Pad (OTP), because any automation can‟t produce any random pad than a human being, and their messages posses same property. The length of Key used in El Gamal encryption and size of OTP determines the level of secrecy offered by the proposed system. Further a discussion is made upon the other dimensions of degree of security provided in such implementation. So as a result an applied approach is presented to design a data security mechanism for which users will use message itself as a One Time Pad and El Gamal Cryptosystem to initiate the operations and subsequent steps will involve simple XOR operations for cryptographic purpose. General Terms Cryptography, Network Security, Public Key Cryptosystem, El-Gamal Algorithm

Proposed Digital Signature Using One Time Pad

Proposed Digital Signature Using One Time Pad

Hybridize Dynamic Symmetric Key Cryptography using LCG

In the present work, a block cipher is presented which deals with a dynamic symmetric key cryptographic method using substitution and transposition technique. In this work a dynamic secret key is generated using Linear Congruential Generator (LCG). The striking feature of the present work is creation of a new secret key for every pair of encryption and decryption operation, thus secret key is a dynamic key. After encryption and decryption operation the dynamic key is discarded. The proposed cryptography method is a process consisting of two rounds of encryption and two rounds of decryption. The key generation algorithm uses SHA-1 hashing scheme to produce key of size 196 bits. This key is used to encrypt plain text of variable size. Since this is a block cipher method authors divide the variable size plaintext into ‘n’ fixed size (49 bit) blocks. The notion of dynamic key has evolved from the concept of the one time pad. Different parts of dynamic secret key are used in different places in order to make it harder for cryptanalysis or attacks.

PERFORMANCE EVALUATION OF MULTICRYPT ENCRYPTION MECHANISM

Multicast communication allows a single message packet to be routed to multiple nodes simultaneously. Membership in a multicast group is dynamic, allowing nodes to enter and leave the multicast session. Besides the benefits, multicast communication presents the challenge of securing the communication. In order to preserve confidentiality the general encryption mechanism used for point to point communications are used. A specific encryption mechanism rather a general one is needed to suit the multicast communication requirements wherein the life time of a secret key is very short and requires a frequent change. Moreover, the next generation wireless networks have very limited resources and need a light weight security mechanism. The proposed cipher, Multicrypt, is similar to the One Time Pad and Hill cipher based on a sub band coding scheme using the principle of Orthogonal Vectors. The proposed cipher is based on the assumption of Computational Diffie Hellman problem and insolvability of Hadamard conjecture. It is designed to have multiple keys to decrypt the message like asymmetric cryptosystem so that a (key) compromise of a member would not lead to compromise of the entire system, less computational and communicational overheads, less storage complexity and there is no need for state-full members. This study also presents an extensive security analysis and the performance analysis with RSA, a public key encryption mechanism used to establish session keys. With the help of security analysis the study proves that brute force attack does not compromise the system. Multicrypt cryptosystem has the capability of dynamically adding and revoking members. The performance of Multicrypt is relatively better in terms of key setup time, encryption time, decryption time, encryption throughput and decryption throughput than RSA in the simulated setup. The proposed cipher is also proved to be secure against IND-CPA and IND-CCA attacks.

Symmetric Key Cryptography using Dynamic Key and Linear Congruential Generator (LCG)

The present work deals with a new symmetric key cryptographic method using dynamic key. The demand for adequate security to electronic data system grows high over the decades. In the present work the authors have used the Linear Congruential Generator (LCG) for generating key. This is a block cipher technique. The advantage of the present method is that for every pair of encryption & decryption operation a new dynamic key is generated thus the process is very hard to break.The cryptography no longer relies on long term shared keys which are vulnerable under cryptanalysis attacks. It is impossible to detect patterns with which to perform cryptanalysis on the dynamic key.In the present work the authors have introduced concept of dynamic key with symmetric cryptography. Dynamic key is similar to one time pad. In this paper, a dynamic key theory is described and mathematically analyzed.In the present method author proposed a cryptography system in which four rounds of encryption & decryption are performed. In each round different parts of dynamic key are applied in order to make it hard against cryptanalysis attacks.

Quantum Secret Sharing of Secure Direct Communication Using One-Time Pad

Instead of sharing some sifted keys, quantum secret sharing of secure direct communication (QSS-SDC) allows a dealer Alice to share her secret message directly with a group of agents, who can then cooperate together to restore her message in a later time. However, we notice that, in order to recover the secret message, most existing QSS-SDC schemes require a quantum memory to store a resulting quantum state. As the technique of quantum memory is still not available today, we present a multiparty QSS-SDC protocol using quantum one time pad, which allows the agents to store their shares with classical binary strings. Moreover, the proposed scheme uses only single photons, which makes it easier to implement with current technology even when the number of the participants becomes large.

Enhanced OneTime Pad Cipher with MoreArithmetic and Logical Operations with Flexible Key Generation Algorithm

The process of exchanging information is called Communication. The basic Communication system involves transmitter, receiver and the channel. The data transmitted by the sender reaches receiver through the channel. The unauthorized parties (cracker,hacker, eavesdropper, or attacker) should not be able to access the information at the channel. Therefore transmitting data securely from the sender to the receiver is a very important aspect. A cryptographic system is unconditionally secure if the cipher text produced by the system does not contain enough information to determine uniquely the corresponding plaintext, no matter how much cipher text is available. A cryptographic system is said to be computationally secure if the cost of breaking the cipher exceeds the value of the encrypted information and the time required to break the cipher exceeds the useful lifetime of the content. One time pad system can be called as unconditionally secure algorithm, if the keys (pad) usedare truly random in nature. In this paper, we are demonstrating that one-time pad can be used as an efficient encryption scheme by involving arithmetic and logical operations. Here we proposed a new key generation technique, to generate a key of any length just by providing a seed value, to encrypt the message. The problem generating key value has been solved by the use of key generation algorithm.

Information security for sensors by overwhelming random sequences and permutations

We propose efficient schemes for information-theoretically secure key exchange in the Bounded Storage Model (BSM), where the adversary is assumed to have limited storage. Our schemes generate a secret One Time Pad (OTP) shared by the sender and the receiver, from a large number of public random bits produced by the sender or by an external source. Our schemes initially generate a small number of shared secret bits, using known techniques. We introduce a new method to expand a small number of shared bits to a much longer, shared key.Our schemes are tailored to the requirements of sensor nodes and wireless networks. They are simple, efficient to implement and take advantage of the fact that practical wireless protocols transmit data in frames, unlike previous protocols, which assume access to specific bits in a stream of data.Indeed, our main contribution is twofold. On the one hand, we construct schemes that are attractive in terms of simplicity, computational complexity, number of bits read from the shared random source and expansion factor of the initial key to the final shared key. On the other hand, we show how to transform any existing scheme for key exchange in BSM into a more efficient scheme in the number of bits it reads from the shared source, given that the source is transmitted in frames.

위치기반 Two-Factor L-OTP 프로토콜

기존 휴대폰에 비해 강력한 연산능력을 가진 스마트폰의 출시 이후 개인 컴퓨터에서 제공되던 온라인 서비스의 영역이 점차 스마트폰으로 확산되고 있는 추세이다. 이러한 기술의 발전은 사용자에게 서비스제공의 시간 및 공간적 제한을 없애 주었지만, 악의적 공격에 쉽게 노출되는 보안상의 취약점을 가진다. 특히 금융권 서비스 이용 시 사용자의 비밀 정보가 교환되므로 더욱 주의를 기울여야 한다. 이러한 보안 문제를 해결하기 위해서는 하나의 세션에 하나의 비밀 키만을 사용하는 OTP(One Time Pad)가 권장되고 있다. 지금까지 스마트 폰에서의 OTP기법들은 기존 환경에 초점을 맞추어 제안 및 구현되어 왔다. 하지만 모바일 환경에서의 보안은 기존 시스템에 비해 공격에 취약할 뿐 아니라 자원적인 한계점을 가진다. 따라서 스마트폰에 적합한 새로운 개념의 OTP의 도입이 요구되어 진다. 본 논문에서는 시간동기화를 통한 T-OTP(Time One Time Pad) 기법과 위치기반 정보를 접목한 L-OTP(Location-OTP) 프로토콜을 제시한다. 제안된 방식은 스마트폰에서 사용자가 가지는 유일한 위치정보를 통해 OTP를 생성한다. After releasing the smart phone equipping the strong computational capability compared to traditional mobil phone, a field of services, which is available on the personal computers, is expanded to smart phone. The development of technology reduces the limited service utilization on time and space but it has a venerability exposing an information to malicious user. Especially we need to more attention when using the financial services which communicate the user's private information. To solve the security problem, OTP(One Time Pad), which uses a private key for a session, is recommended. OTP techniques in smart phone having focused on traditional environments have been proposed and implemented. However, security over mobile environments is more vulnerable to attack and has restriction on resources than traditional system. For this reason, definition of proper conceptual OTP on smart phone is required. In the paper, we present the L-OTP(Location-OTP) protocol, using T-OTP(Time One Time Pad) technique with location information. Proposal generates the OTP using unique location information which is obtained in smart phone.

Crypt analysis of two time pads in case of compressed speech

Keystream reuse, also known as the two time pad problem, is a well known weakness in stream ciphers. The implementers of the cryptographic algorithms are still underestimating this threat. The keystream reuse exploitation techniques presented so far assume the underlying plaintext to be textual data and all the heuristics presented previously are based on the language characteristics of the underlying text based data, which fail when compression is applied on the plaintext before encryption. This paper presents exploitation techniques for two time pads in case of stream ciphered digitized and compressed speech signals. In this paper we show that how an adversary can automatically recover the digitized speech signals encrypted under the same keystream provided the language (e.g. English) and digital encoding/compression scheme details of the underlying speech signals are known. Our technique of cryptanalysis is based on the modeling of the speech parameters by exploiting the inter frame correlations between each components of the speech vectors in different frames and then using these models to decode the two speech signals in the keystream reuse scenario. The technique is flexible enough to incorporate all modern speech coding schemes based on parameter or hybrid encoding and compression techniques. The simulation experiments have showed promising results for most of the present day speech digitization and compression techniques.

Rapid programmable/code-length-variable, time-domain bit-by-bit code shifting for high-speed secure optical communication

We propose and experimentally demonstrate a time-domain bit-by-bit code-shifting scheme that can rapidly program ultralong, code-length variable optical code by using only a dispersive element and a high-speed phase modulator for improving information security. The proposed scheme operates in the bit overlap regime and could eliminate the vulnerability of extracting the code by analyzing the fine structure of the time-domain spectral phase encoded signal. It is also intrinsically immune to eavesdropping via conventional power detection and differential-phase-shift-keying (DPSK) demodulation attacks. With this scheme, 10 Gbits/s of return-to-zero-DPSK data secured by bit-by-bit code shifting using up to 1024 chip optical code patterns have been transmitted over 49 km error free. The proposed scheme exhibits the potential for high-data-rate secure optical communication and to realize even one time pad.

Lightweight mutual authentication protocol for securing RFID applications

Radio frequency identification (RFID) is a technology with a great potential in many industries and a wide spectrum of possible uses. However, it is very much vulnerable as it faces some major security challenges and threats. There currently exist several RFID technologies without proper security enhancement such as privacy and authentication. Thus, this paper addresses security, privacy and authentication and proposes a lightweight mutual authentication suitable to be implemented for the passive RFID tags. The proposed protocol is simple, low cost and low power consumption as well as requires low computation as it uses a light shrinking generator that could be considered an alternative for the use of the well known one time pad algorithm.

Exogenous Probabilistic Computation Tree Logic

We define a logic EpCTL for reasoning about the evolution of probabilistic systems. System states correspond to probability distributions over classical states and the system evolution is modelled by probabilistic Kripke structures that capture both stochastic and non–deterministic transitions. The proposed logic is a temporal enrichment of Exogenous Probabilistic Propositional Logic (EPPL). The model-checking problem for EpCTL is analysed and the logic is compared with PCTL; the semantics of the former is defined in terms of probability distributions over sets of propositional symbols, whereas the latter is designed for reasoning about distributions over paths of possible behaviour. The intended application of the logic is as a specification formalism for properties of communication protocols, and security protocols in particular; to demonstrate this, we specify relevant security properties for a classical contract signing protocol and for the so–called quantum one–time pad.